Many of us have experience with directors changing subtle things in their movies, ranging from the color that a character wears, to the accent that they speak with (although changes usually aren't that extreme). But do directors have too much control? Many complaints I've heard are based on the fact that directors make changes that mar the original story. They don't do enough to fix the plot, and sometimes they completely changed the significance of this character. We'll go through a couple examples, and I'll let you decide for yourself if directors are as bad as they say.
George is famous (or infamous) for changing his films in the editing room, deleting certain aspects, changing scenes, and making his movies less controversial. A New Hope is reputed to have the most changes, as said in a video made by a fan named, HelloGreedo. You can see his first episode (it has 7 parts) below and his channel here.
These changes have outraged fans, who believe that the movies should stay in their original condition (most of them are irate over the Han/Greedo shot first thing), while others say that the films are George's creation, to do with what he wishes. both arguments have their points, but I think that fans need to come to terms with the fact that the directors will almost always change something. But on the flip side, vaguely following an established plotline is not a way to endear fans to your movies. Speaking of plotlines...
Joss Whedon is a more recent director. He has been the one in charge of the course that Marvel movies have taken since he directed Marvel's The Avengers in May of 2014. He has since been blamed for the course that the movies are taking, and the confusing plotlines of the movies. The reason why most of the fans are upset is because the plot doesn't follow the comics closely enough. Tony did not create Ultron with Bruce Banner, Ant-Man does not start out as a program for soldiers, and others. The thing is, though, that the main point is still the Infinity Stones. We can't complain too much about the plot, because starting with Iron Man in 2007, the whole Marvel line was revamped. So them not sticking to the comics precisely is not that big a deal in the grand scheme of things.
So, there you have it. Are directors insufferable tyrants, or are the fans fanboying to hard? It is up to you, dear reader, so think on. The choice is yours.